Apparatus for continuous coating of elongated articles



Nov. 13, 1962 F. E. TURNER 3,

APPARATUS FOR CONTINUOUS COATING OF ELONGATED ARTICLES Filed Feb. 6, 1959 '7 Sheets-Sheet 1 IN VENTOR.

FRANK E. TU RNER ATTORNEYS.

Nov. 13, 1962 F. E. TURNER 3,063,409

APPARATUS FOR CONTINUOUS COATING OF ELONGATED ARTICLES Filed Feb. 6, 1959 7 Sheets-Sheet 2 .R. H m N mm m w w WE. /+A K a W F 9 m Nov. 13, 1962 F. E. TURNER 3,063,409

APPARATUS FOR CONTINUOUS COATING 0F ELONGATED ARTICLES Filed Feb. 6, 1959 7 Sheets-Sheet 3 ATTORNEYS Nov. 13, 1962 F. E. TURNER 3,063,409

APPARATUS FOP. CONTINUOUS COATING OF ELONGATED ARTICLES Filed Feb. 6, 1959 7 Sheets-Sheet 4 INVENTOR.

FRANK E. TURNER BY 2 K g W Q/W ATTORNEYS N v- 13, 1 2 F. E. TURNER 3,063,409

APPARATUS FOR CONTINUOUS COATING 0F ELONGATED ARTICLES Filed Feb. 6, 1959 7 Sheets-Sheet 5 INVENTOR. FRANK E. TURNER ATTORNEYS.

Nov. 13, 1962 F. E. TURNER 3,063,409

APPARATUS FOR CONTINUOUS COATING OF ELONGATED ARTICLES Filed Feb. 6, 1959 7 Sheets-Sheet 6 S &

' 37 INVENTOR. ii 39 9 FRANK E. TURNER 19 x z BY M... x 4 v@.

ATTORNEYS.

Nov. 13, 1962 F. E. TURNER 3,063,409 APPARATUS FOR CONTINUOUS COATING OF ELONGATED ARTICLES Filed Feb. 6, 1959 '7 Sheets-Sheet 7 SUI INVENTOR.

FRANK E. TURNER Z Z JMW ATTO E NEYS.

United States Patent Ofitice 3,953,4d9 Patented Nov. 13., was

APPARATUS FOR CONTINUOUS COATING (3F ELONGATED ARTICLES Frank E. Turner, Pittsburgh, Pa., assignor, by mesne assignments, to RlaW-Knox Company, Pittsburgh, Pa., a corporation of Delaware Fiietl Feb. 6, 1959, Ser. No. 791,612

I2 (Tiaims. (iCl. 118-426) This invention relates to the treatment of elongated articles with liquid material and more particularly to an improved method of and apparatus for the continuous hot galvanizing of metal products such as pipe, bars, shapes, etc.

In the accompanying drawings and the following specification there is described and illustrated a method of and apparatus for hot galvanizing metal pipe, but it will be understood that my invention may advantageously be employed in numerous other applications where it is desired to treat elongated articles such as pipe, bars, shapes, etc., in a liquid bath. Accordingly where reference is made to galvanizing herein, it is intended to include not only galvanizing per se but also other coating operations such as the application of paint, enamel, cleaning or pickling solutions, etc., and where reference is made to pipe it is intended to include other elongated articles such as bars, shapes, etc.

In galvanizing steel pipe it is common practice to submerge the pipe in a bath of molten zinc so that both the inner and outer surfaces of the pipe are completely covered. The lengths of pipe are then withdrawn and drained. Various schemes involving conveyors or the like have been proposed for depositing the lengths of pipe in the galvanizing tank. The pipes have customarily been manually lifted from the galvanizing bath and brought into engagement with suitable rolls or conveyors which remove the pipes from the tank. With such prior procedures there is no way of insuring that the pipes are withdrawn from the bath in the same order that they enter the bath, and accordingly the time of immersion may vary to a considerable degree resulting in undesirable variations with respect to the coating thickness and the quality of the finished coated product.

It is an object of the present invention to provide a fully automatic continuous pipe galvanizing machine or the like wherein the pipes or other elongated articles maintain the same positive relation to each other throughout the entire process, i.e., the pipes pass through the processing steps and are withdrawn from the galvanizing tank in exactly the same order as they enter the tank, and every pipe is subjected to exactly the same treatment. Another object of my invention is to provide means for automatically submerging hollow elongated articles in a coating bath whereby one end of each article is caused to enter the bath initially at a lower level than the other end and, during travel of the pipe through the bath, the longitudinal axis of the pipe is tilted so that the coating bath will flow freely through the inside of the article without entrapment of air, and whereby, after complete immersion, the pipe will be withdrawn from the bath with the aXis tilted in the opposite direction from its position on entry. A further object of my invention is the provision of a means for continuously pickling and cleaning a series of pipes or the like and causing same to be submerged in and withdrawn from a galvanizing tank in sequential order. My invention also contemplates improved means for withdrawing the pipe from the coating tank and removing excess zinc or other coating material therefrom in a continuous and automatic manner.

The above and other objects of my invention will appear from the following description of an apparatus for galvanizing steel pipe or the like, reference being made to the accompanying drawings in which:

FIGURE 1 is a plan view, partly in horizontal cross section, illustrating my invention as incorporated in pipe galvanizing apparatus;

FIGURE 2 is an enlarged vertical cross-sectional view taken substantially on line 22 of FIGURE 1;

FIGURE 3 is a vertical cross-sectional View taken substantially on line 3-3 of FIGURE 2, the pipe conveying and sinking screws, however, being illustrated in the positions they assume as a pipe is being moved endwise out of the galvanizing bath;

FIGURE 4 is an end elevational view taken substantially on line 4-4 of FIGURE 1 and illustrating the internal and external coating control stations and the magnetic roll conveyor means for removing coated pipe from the galvanizing tank;

FIGURE 5 is a vertical cross-sectional view taken substantially on line 55 of FIGURE 1 and illustrating the indexing transfer means for moving pipe from the magnetic roll conveyor to the internal coating control station, the water bosh, the spray coating unit, etc.;

FIGURE 6 is an enlarged view, generally similar to FIGURE 3 but also illustrating in phantom lines the sev eral positions of the longitudinal axes of the pipes as they move into and through the galvanizing kettle;

FIGURE 7 is an enlarged vertical cross-sectional view through the galvanizing kettle and illustrating the front conveying screw;

FIGURE 8 is a vertical cross-sectional view taken substantially on line 38 of FIGURE 7 and illustrating the discharge end of the front conveying screw;

FIGURE 9 is a view generally similar to FIGURE 7 but illustrating the rear conveying screw;

FIGURE 10 is a fragmentary cross-sectional view taken substantially on line Iii1t) of FIGURE 9 and illustrating the form of the discharge end portion of the rear conveying screw;

FIGURE 11 is a fragmentary view of a modified form of the galvanizing section of my apparatus in which a flux tank is provided immediately ahead of the galvanizing kettle; and

FIGURE 12 is a View generally similar to FIGURE 7 but illustrating a modified form of a conveying screw having a double thread and particularly adapted to handle pipes of relatively small diameter in pairs.

Referring particularly to FIGURES l and 2, the automatic continuous pipe galvanizing line illustrated includes a loading rack comprising a plurality of inclined skid members 1 adapted to receive bundles of pipe from storage or previous processing operations. On these racks the pipes P are arranged in a single layer and rolled downwardly by gravity. At the lower end of the loading rack the pipes are picked up by an automatic selector unit comprising a plurality of rotating conveying screws 2 which are simultaneously driven by suitable gearing and shafting such that their rotation is in a direction to advance the pipes one at a time in a direction perpendicular to their length. The pitch of the screws 2 and the shape of the entering ends of the threads thereon is such that one individual length of pipe will be removed from the loading skids I at every 360 of rotation of the screws.

Thus the pipes P are removed one at a time from the skids I and are individually advanced in spaced apart relation in a direction normal to their longitudinal axes. From the screws 2 the pipes are delivered to a rotating purge chamber 3 in which a vaned rotary gas seal and transfer wheel 4 is mounted. As illustrated, the wheel 4 has a plurality of vanes (six as illustrated) separating the unit into a plurality of compartments. As seen in FIGURE 1, the shaft 5 on which the transfer wheel 4 is supported is connected by a chain 6 to the drive shaft 2 for the rotating screws 2, and thus the rotation of the screws 2 is synchronized and interlocked with the transfer wheel 4 so that the screws 2 will successively discharge pipes, one into each of the compartments formed by the vanes of the transfer wheel. As seen in FIG- URE 2, the wheel 4 rotates in clockwise direction and has a fairly close fit with the walls of the chamber 3 so that a seal is provided for preventing undesired entry or escape of atmosphere to or from the furnace F. A controlled atmosphere of suitable type, to be referred to later, is caused to enter the compartments formed by the rotating wheel 4 in the purge chamber 3 to purge the air from the compartments and pipes contained therein before they enter the furnace.

Immediately beyond the purge chamber and rotating transfer wheel in the direction of pipe travel is a chain transfer or conveyor comprising a plurality of conveyor chains 7 which extend through the furnace F and carry the lengths of pipe P therethrough. Screw conveyors may be employed in place of chains 7 if desired.

Each of the chains 7 is supported on end sprockets 8 and 9 mounted respectively on shafts 10 and 11 and is guided by suitable idler sprockets as seen as 12, 13 and 14 in FIGURE 2. Floating counterweights 15 maintain the desired tension on the chains 7 which are provided with spaced upstanding lugs '7 which engage the pipes P and move them on suitable rails or skids 7 through the furnace F. The shaft 10 which supports the sprockets 8 is connected to the shaft 5 of the rotary transfer Wheel 4 by chain 15 so that there is positive synchronization of the automatic selector screws 2, the vaned transfer wheel 14, and the chains 7 or conveyor screws. As the lugs 7 on the individual chains 7 are transversely aligned, the pipes will be rolled thereby over the skids 7 in individual sections or compartments in a direction perpendicular to their longitudinal axes.

The furnace F, as best seen in FIGURE 2, consists of an entry chamber 16, a heating chamber 17, and an exit end and galvanizing machine housing section 18. In the galvanizing apparatus shown in FIGURES l and 2 a controlled atmosphere is maintained within the furnace F suitable to effect gas pickling of the pipe prior to galvanizing. With such an arrangement it is unnecessary to subject the pipes to the usual liquid acid pickling before they enter the galvanizing furnace or preheater although, if desired, liquid pickling or cleaning may be employed as will be referred to later and in which case the furnace atmosphere will be a reducing gas which will maintain previously pickled pipe in a clean condition while heating. The length of the heating chamber 17 of the furnace F is such that, as the pipes travel therethrough, they will be heated to a temperature proper for hot galvanizing. Heat may be supplied to the furnace by any suitable means (not shown) such as electrical resistance heating elements, fluid fuel fired radiant heating tubes, gas burners, etc., and sliding gates 17 may be provided for closing off the furnace chamber if desired.

Disposed within the galvanizing chamber section 18 of the furnace F is a galvanizing machine unit which includes a galvanizing kettle 19, adapted to contain a bath of molten zinc, the level of which is indicated at Z in FIGURES 6, 7 and 9, and a pair of spaced pipe conveying and sinking screws generally indicated at S and S. These screws are mounted respectively on shafts 20 and 21 which extend across the top of the galvanizing kettle 19 and through the end wall 22 of the furnace F. A suitable frame structure 23, Within the exit end portion 18 of furnace F, is provided for supporting shafts 20 and 21, and the feed screws S and S are so disposed that their entering or pick-up ends 29 and 30 (lefthand as seen in FIGURE 2) are positioned to take the pipes P one at a time as they leave skids 7 at the exit end of the conveyor chains 7 and move them in an advancing series on spaced guides or skids G (see FIG- URE 3) toward the galvanizing kettle 19.

The shaft 11 which carries the sprockets 9 for the conveyor chain 7 is connected through gear box 24 and shaft 25 to gear box 26 which is driven by the motor 27. Shaft 28 extends from gear box 26 and has geared connection to shafts 20 and 21 which support the conveying screws S and S. This interconnection of the conveyor screw drive and the chain drive provides positive synchronization of the chains 7 and the screws S and S so that each complete rotation of the screws a length of pipe P will be picked up from the conveyors 7 and moved along the guides or skids G by the entering or pick-up portions 29 and 30 respectively of screws S and S (see FIGURES 7 and 9).

As clearly seen in FIGURE 3, the pipe guides or skids G are spaced longitudinally of the galvanizing kettle 19 and are offset from the front and rear conveying screws S and S. Although the size and contour of the several guides G vary for reasons which will be later referred to, they each have a horizontal entering portion 31, the top edge of which is disposed approximately at the level of the outside of the threads 32 and 33 on the pick-up portions 29 and 30 of screws S and S. Just beyond the entering portions 31 of guides G are downwardly inclined portions 34- which extend into the galvanizing kettle 19 and have their upper edges sloped to impart the desired travel of the pipes P into the coating bath in kettle 19.

In addition to the pick-up portions 29 and 30 of the screws S and S, each has flaring or enlarging portions 35 and 36 respectively. The pick-up thread portions 32 and 33 of screws S and S continue on the flaring portions 35 and 36 thereof and are indicated at 35 and 36. As seen in FIGURES 7 and 9, the guides G and the enlarging threaded portions 35 and 36' of screws S and S are so correlated that the pipes P will be supported on the inclined portions 34 of the guides G and advanced downwardly into the coating bath in the kettle 19 by the action of the threads 35 and 36.

The guides G each have bottom portions 37 over which the pipes P are traversed by the threads of the front and rear conveying screws S and S. In addition, each of the guides G has a support portion 38, the upper part of which is adapted to rest on the top of the galvanizing kettle 19 and thus hold the guide in proper position therein while permitting it to be removed when it is desired to clean out the kettle or for any other reason. As indicated in FIGURE 3, the guides G are preferably arranged in pairs that are joined together by connecting bars 39. This assists in properly locating and maintaining the guides G in position in the galvanizing kettle 19.

As previously mentioned, the location of the angle of slope of the portions 34'01 the several guides G varies. As seen in FIGURE 7, the guide G that is immediately adjacent the front conveying and sinking screw S has a portion 34 which is inclined at a lesser angle than the corresponding portion 34 of the guide G adjacent rear conveying crew S and seen in FIGURE 9. In these two FIGURES, and also in FIGURE 6, the pipes illustrated are given the same reference characters.

It will be observed that the pipe indicated at J in both FIGURES 7 and 9 has just been picked up by the first thread of the screws S and S andis starting its travel over the horizontal portions 31 of the guides G. The screws S and S are so arranged, and their driving connections are so interlocked, that the pipes are traversed over the skids G with their longitudinal axis extending at right angles to the axes of the conveying screws. The pipe K as seen in both FIGURES 7 and 9 is in the second pitch of the conveying screws while the pipe L has been moved along the horizontal portions 31 of skids G until both ends are disposed directly above the left hand side wall of the galvanizing kettle 19. The effect of the difference in the location of the slope of the inclined portions 34 of the guides G becomes apparent from the positions of the portions of the pipe M that are seen in FIGURES 7 and 9. Thus the front end portion of pipe M (front being identified as the end which exits first when the pipe is moved longitudinally out of the galvanizing kettle as will be later described), as seen in FIGURE 7, has started down the incline 34 of the adja cent guide G while the rear end of the same pipe M, as seen in FIGURE 9, is still resting on the horizontal portion 31. The enlarging or expanding threads 35 and 36 of the screws S and S respectively are so formed that they will maintain the pipes being traversed with their longitudinal axes substantially perpendicular to the axes of the conveying rolls S and S at all times.

From the positions of pipe M seen in FIGURES 7 and 9 it will be apparent that the front end of a pipe, as it begins its movement into the galvanizing kettle 19, is somewhat lower than its rear end. The reason for this is to facilitate the free and immediate entry of the molten zinc into the interior of the pipe and to prevent entrapment of air therein. The contours of the inclined portions 34 of the guides G and of the enlarging screw portions 35 and 36 of screws S and S are such that, as a pipe is advanced into the galvanizing bath, its longitudinal axis is tilted so that the front end of the pipe enters the bath before the rear end. As the pipe is fed further into the bath, the rear end is lowered without corresponding lowering of the front end until, when the pipe reaches the bottom of the inclined portions 34 of the guides G, it is fully submerged in the molten zinc and its longitudinal axis is substantially horizontal (see pipe Q in FIGURES 6, 7 and 9).

The several positions of the pipes being submerged in the coating bath that are shown in FIGURES 7 and 9 are also indicated by phantom center lines in FIGURE 6. Thus in FIGURE 6 the center line of pipe L of FIG- URES 7 and 9 is seen at L, and it will be observed that at this point the pipe is horizontal and Well above the zinc level Z. The pipe M of FIGURES 7 and 9, as seen by its center line M in FIGURE 6, has had its front end tilted downwardly, and pipe N of FIGURES 7 and 9, while its axis is maintained substantially parallel to the position of the axis of pipe M, has been moved bodily downwardly until its forward end has entered the zinc bath. Pipe Q of FIGURES 7 and 9 has reached the bottom of the inclined portions of guides G and, as seen in FIGURE 6, is now disposed with its axis horizontal and is completely submerged below the level of the zinc in the kettle 19. The pipe P that is seen in full view in FIGURE 6 has, as will be more fully described later, reached the exit grooves and the conveying screws S and S and is steeply inclined for angular removal from the kettle 19.

Just beyond the last pitch of the thread 35 on front screw S is an annular groove 4% to which the last pitch of the thread 35 connects and into which the pipes are moved by said thread. This groove Ali is circular, as seen in FIGURE 8, and has a permanent magnet portion 41 which extends around a portion only of the base of the groove. At the end of the enlarging thread 36 of conveying screw S is a groove 42 formed on an enlarged cam portion indicated at 43. A permanent magnet 44 is mounted in the cam portion 43 and is effective over the portion of the bottom of the groove 42 that is most remote from the shaft 21 (see FIGURE 3). In the guides G that are supported adjacent the rear conveying screw S, elongated slots 45 (seen in FIGURE 9) are provided. These slots permit the cam portion 43 of screws S to rotate therethrough and also permit the pipes that are conveyed into the grooves 42 by the threads 36 to be lowered as the enlarged part of the cam portion approaches its lowest position.

In the operation of the galvanizing apparatus just described, the pipes P are picked up from the ends of the conveyor chains 7 and are traversed by conveying screws S and S successively over the horizontal portions 31 of the guides G and down into the galvanizing bath in the kettle 19, the axis of each pipe being tilted during movement into the galvanizing bath so that the front end enters first and then the rear end being moved down so that the pipe is horizontal when fully submerged in the bath. The pipes are traversed through the bath in a direction perpendicular to their length and ultimately move into the grooves 40 and 42 on screws S and S respectively. When a pipe first enters these grooves, its axis is substantially horizontal but, as the screw S continues to rotate, the rear end of the pipe is further submerged into the galvanizing kettle to a position such that the pipe will have a substantial inclination upwardly (for example about 18). As seen in FIGURES 3 and 6, as the rear end of the pipe is lowered, the front end will be elevated somewhat because it pivots on the screw S a short distance back from the front end.

As the conveyor screws S and S rotate, the permanent magnet portions 41 and 4-4 thereof will hold the pipe firmly against the base of the grooves 40 and 42 and cause the pipe to be fed longitudinally in the direction of its length. As seen in FIGURE 3, two permanent magnet rolls 50 and 51 having V-grooves on their outer surface to assist in gripping and guiding the pipes, are mounted just beyond conveying screw S in the direction of pipe travel. The axis of roll 51 is vertically offset from the axis of roll 50 so that, as a pipe P is moved into its upwardly inclined position by the action of the cam portion 43 of rear conveying screw S and is moved longitudinally by magnets 41 and 44 on screws S and S, the forward end of the pipe will engage magnetic rolls 50 and 51. These rolls are driven by suitable means (not shown) and will continue to move the pipes P in the direction of their length completely out of the coating liquid in kettle 19 after the magnets 44 and 41 have moved out of contact with the pipes. The rearward inclination of the pipes as they are withdrawn from kettle l9 insures prompt and complete draining of the coating liquid from the pipes back into kettle 19.

The advancing ends of the pipes P, as they are moved out of the galvanizing kettle 19, are moved into engagement with the lower rolls of a magnetic roll conveyor unit that is best seen in FIGURE 4. This unit includes at its lowermost end a pair of driven permanent magnet rolls 52 and 53 which are aligned with the path of travel of the pipes as they exit fromthe galvanizing tank. These rolls 52 and 53 engage and pick up the pipes as they come along. Supported on an inclined frame 54 are a series of driven electromagnetic rolls 55, 56, 57 and 58 which are adapted to be energized and d e-energized by suitable electrical connections and controls (not shown) in a well-known manner.

As seen in FIGURE 4-, the pipe P has been moved in the direction of its length by the permanent magnet rolls 52 and 53 and has engaged the electromagnet rolls 55, 56, 5'7 and 5%, which are energized at all time except when the limit switch 59 is actuated. The depending contractor 59 of limit switch 59 extends into the path of the end of the pipe P. As seen in FIGURE 4, the pipe P has left the permanent magnet rolls 52 and 53 and is supported by the energized electromagnet rolls. The leading end of pipe I is just about to operate the limit switch 59 and, when this occurs, the electrical connection to the electromagnet rolls 55, 56, 5'7 and 58 is broken and the rolls immediately become de-energized permitting the pipe P to drop onto the movable racks 64b of the indexing transfer units which are generally indicated at T in FIGURES 4 and S.

A plurality (three as illustrated) of the indexing transfer units T are spaced along and below the pipes that are conveyed by the electromagnet rolls SS, 56, 57 and 53. As seen in FIGURE 4, the units T are supported on an inclined frame structure 61. Each unit T includes a movable rack 6t? pivotally supported on a pair of parallel arms 62 which are in turn mounted on driven shafts for rotation in the direction of the arrow in FIGURE 5. A second movable rack 63 is similarly supported on arms 64 which are also arranged in parallel relation and on the opposite side of the main frame 65 of unit T from the arms 62. The arms 62 and '64 are supported on driven shafts which are interconnected, as by suitable gearing or the like, so that the shafts will rotate in the same direction and carry therewith the movable racks 60 and 63 While the upper faces thereof will be maintained in a horizontal plane at all times.

As clearly seen in FIGURE 5, the arms 64 are disposed 90 in advance of the arms 62 and, because of the interconnection of the drive shafts of the arms 62 and 64, this angular spacing remains constant. A stationary transfer rack 66 is mounted on the main frame 65 of the units T. The arms 62 and 64 are disposed on opposite sides of frame 65 and thus the stationary rack 66 is disposed between the paths of the movable racks 60 and 63.

As shown in FIGURE 5, the movable racks 60 and 63 are in their normal or at-rest positions. Suitable single revolution control means (not shown) are provided for the drive means which operates the shafts on which arms 62 and 64- are mounted. The operation of this single revolution control means is such that when a pipe P engages the limit switch 59 and de-energizes the magnet rolls 5558 and a pipe P is dropped from these rolls onto the movable rack 60, the rotary movement of the racks is started and continues through 360 whereupon the racks stop in their at-rest positions and remain their until another single revolution cycle is started by engagement of the limit switch 59 by the next pipe. When the arms 62 have moved counterclockwise through 90 from the position seen in FIGURE 5, the pipe receiving notches on the top face of rack 60 will be aligned with the pipe receiving notches on the top face of the stationary rack 66. When rack 63 is in its at-rest position seen in FIGURE 5, a pipe, indicated at P will be supported thereon. This pipe is also seen at P' in FIGURE 4 and is disposed in alignment with the internal coating control station as will be later described. During the first 90 of counterclockwise rotation of the rack 63, which occurs with the above referred to rotation of rack 60, the pipe P disposed thereon will be dropped down onto the adjacent movable chain type cooling bed B which carries the pipes to the water bosh 68.

As the movable racks 6% continue their rotation beyond the 90 point, the pipe P will be left on the stationary racks 66. When the movable racks 63 have traveled through 180, they will be aligned with the stationary racks 6'6, and as the racks 63 continue to move, they will pick up the pipe P which was previously left on the stationary transfer racks 66 by the movable racks 60. Continuing rotation of the racks 60 and 63 will bring racks 60 back to the position shown in FIGURE ready to receive another pipe from the electromagnet rolls 5558 and will return racks 63 into their horizontal at-rest positions seen in FIGURE 5 with a pipe supported thereon ready to be subjected to the operation of the internal coating control means.

From the above, it will be seen that the indexing transfer units T provide means for timed transfer of pipes from the conveying rolls 5558 to the internal coating control station and further transfer from this coating control station to the movable chain type cooling bed B. The bed B includes a pair of chain conveyors 67 and a plurality of spaced supporting rails 67 (see FIGURE 1). The discharge ends of these rails 67 are all disposed in the same level above the top of the water bosh or tank 68. As the coated pipes move over the rails 67', the Zinc coating cools and solidifies. The discharge end of the rails 67' are curved downwardly as seen at 67" to faciliate the desired free fall of the lengths of pipe into the water in the bosh or tank 68. Chain conveyors '70 pick up the pipes as they are dropped into the bosh 68 and remove them therefrom. These conveyors pass over a pan. or trough 70 which is adapted to collect surplus coating liquid which may be sprayed onto the pipes, as they move over the pan 70, by suitable spray heads or the like (not shown). This spray is preferably of a solution which inhibits the formation of so-called white rust or bloom on the surface of the galvanized pipes. After leaving the conveyors 70, the pipes reach the inspection table 71 from which they may be removed for further processing, storage or shipment.

When the pipes P are withdrawn from the bath of molten zinc in the galvanizing kettle 19, they pass through an exterior coating control station which is located between the permanent magnet rolls 52 and 53 and consists of an annular pipe 78 connected to a suitable source of steam or air under pressure and having a plurality of small holes or jets adapted to direct streams or steam or air over the entire outer surface of the pipes P as they pass lengthwise through the opening in the annular pipe 78. The effect of the impinging jets of air or steam on the molten zinc on the outside of the pipes P is to remove excessive amounts and equalize the coating so the desired uniform thickness is obtained.

In order to control the thickness of the coating on the interior of the pipes P, the internal coating control station generally indicated at C in FIGURE 4 is provided. Before describing unit C, however, it is pointed out that the movable rack 63 on the indexing transfer unit T that is disposed under the electromagnet roll 58 (FIGURE 4) has a permanent magnet associated therewith and efiective on the pipes supported thereby so that the pipe P is held on this rack 63 against backward lengthwise movement during operation of the internal coating control apparatus thereon.

The unit C includes a horizontally adjustable supporting frame 72, a slide or guide member '73, and a cross head 74- slidable in said guide 73 and connected to a connecting rod 75 which in turn is operated by crank unit 76 mounted on a suitable shaft and driven by suitable means. A bell mouth pipe end engaging member 77 is carried by the cross head 74 and is provided with air or steam pressure connections adapted, when the bell mouth is in engagement with the forward end of a pipe P, as seen in FIGURE 4, to discharge air or steam under pressure to the interior of the pipe while sealing the end thereof. This air or steam, or other fluid under pressure, blows out the excess coating material from the interior of the pipe.

By means of the crank 76 and connecting rod 75, the bell 77 may be withdrawn from its operating position to permit the pipes P to be moved into and out of internal coating control position. When a pipe has reached this position (indicated at P in FIGURES 4 and 5), the crank '76 is operated to move the bell 77 into tight engagement with the end of the pipe. The air or stream under pressure is then discharged through the pipe by suitable automatic control valve means, and the internal coating control operation is carried out. The bell 77 is retracted by further rotation of the crank 76 upon completion of the coating control operation and before the next single rotation cycle of the support members 63 of indexing transfer units T.

From the above description, it will be observed that I have provided a completely automatic apparatus for conveying elongated articles to and through a coating bath, which apparatus subjects each successive article to exactly the same treatment as each other article. In the pipe galvanizing apparatus shown in FFGURES 1 and 2 the pipe cleaning or pickling is effected by a gaseous atmosphere,

and with such treatment the articles do not need to be fluxed prior to coating. However, if the pipe is cleaned by pickling in an acid bath in well-known manner, the furnace 17 is used only for bringing the pipes up to proper galvanizing temperature in a reducing atmosphere, and a flux tank 80 may be provided ahead of the galvanizing tank 81 as seen in FIGURE 11. The conveying end sinking screw S" is provided with an entering portion 82 which takes the pipes from the furnace, a double inclined fluxing portion 83 which moves the pipes down into the flux bath in tank 89 and then lifts them out again, a horizontal transfer portion 84 which carries the pipes after they are withdrawn from the fluxing bath to the galvanizing tank 81, and a galvanizing portion 35 generally similar to the corresponding portion of screw S of FIGURE 2. The screw S is the front conveyor screw, but it will be understood that the rear conveyor screw for an installation including a fluxing bath would be generally similar to the rear conveyor screw of the apparatus of FIGURES 2 and 3 except for the addition of the forward part of the screw which moves the pipes into and out of the flux tank. By properly contouring the skid or guide members which support the pipes through the flux tank 89, the desired entry into and exit from the tank may be provided.

In the apparatus described hereinabove the threads on the conveying screws S, S and S" are single. It will be understood that the maximum diameter pipe that may be handled by such an apparatus is slightly less than the pitch of the thread, i.e., if the minimum pitch of the thread of the screw S, seen in FIGURE 2, is five inches, the maximum diameter pipe that can be handled thereby will be less than five inches outside diameter. When such an apparatus is used for handlnig small pipe, for example under two inches diameter, there is considerable waste of machine capacity and a corresponding reduction in production output. To increase production, when small size pipes are being handled, it is proposed to employ conveying and sinking screws having double threads, as seen in FIGURE 12. In this figure the screw 8" is a front conveying screw and difiers from screw S of FIG URE 2 largely in that it is provided with a double thread. Thus, one thread of screw 8 is indicated at 86 while the next or second thread is indicated at 87. The pitch or lead of these threads at the entering (left) end of screw 5'' is increased in order to facilitate removal of the pipes from the conveyor 88, but in the main body of the screw the pitch of the threads 36 and 87 is substantially the same as that of the thread 32 of screw S.

If, for example, the single thread screw S of FIGURE 2 is adapted to handle pipe up to four inch diameter, then the double thread screw 3'' can handle two pipes of about two inch diameter in the same lineal space. Thus, by means of the double thread conveying screw shown in FIGURE 12, the output of the machine, when operating on small sizes of pipe, may be about doubled over that which could be obtained if the single thread screw S were used at all times. In order to facilitate quickchanging the conveying screws, the portions of the furnace housing above these elements are removable.

It will be noted that the magnetic rolls 5%, 51, etc. are illustrated as having two pipe receiving grooves therein. These double grooves are provided so that when the double thread screw 8 is used and the pipes are moved through the galvanizing kettle in pairs, they are handled in pairs as they are moved longitudinally out of the galvanizing kettle. In like manner, the supporting edges of the racks 63', 63 and 66' of the indexing transfer units T are illustrated as having two pipe receiving notches. This also is to permit them to be used with double thread conveying and sinking screws as shown in FIGURE 12.

From the above description, it will be understood that my improved appartus provides a fully automatic coating line for elongated articles, particularly suited for the galvanizing of steel pipe or the like. With my apparatus, each article is positively maintained in the same relation to the other articles throughout the coating procedure. Because of the assured first-in-first-out sequence of handling the product, each article is given exactly the same treatment, resulting in uniformly coated 1G product. Extremely hazardous and awkward manual handling of product in conventional galvanizing lines is presently common practice. In addition to eliminating the occupational hazards of galvanizing, my apparatus may be operated with a minimum of manpower and at a high rate of production.

Although I have described the illustrated embodiments of my invention in considerable detail, it will'be understood that variations and modifications may be made in the particular design and proportions of the elements making up my apparatus. Accordingly, I do not wish to be limited to the exact structures and arrangements herein shown and described but claim as my invention all embodiments thereof coming within the scope of the appended claims.

I claim:

1. In combination with a coating tank for elongated articles, means for conveying articles to said tank, a conveying screw supported with its axis extending across said tank in a direction transversely of the length of the elongated articles brought to said tank by said means for conveying said articles, said screw having a portion of uniform diameter disposed above the coating liquid level in said tank and a portion of progressively increasing diameter extending below the coating liquid level in said tank, means for supporting said elongated articles in said tank in feeding engagement with said conveying screw, means for rotating said conveying screw in a direction to feed said articles from said conveying means into said tank in a direction transversely of the length of said articles, and means for removing said articles from said tank.

2. In combination with a coating tank for elongated articles, means for conveying said articles to said tank, a pair of spaced conveying screws supported with their axes parallel and extending across said tank in a direction transversely of the length of the elongated articles brought to said tank by said means for conveying said articles, said screws each having a portion of uniform diameter disposed above the coating liquid level in said tank and a portion of progressively increasing diameter extending below the coating liquid level in said tank and nonadvancing grooves at their delivery ends, means for supporting said elongated articles in said tank in feeding engagement with said conveying screws, means for rotating said conveying screws in a direction to feed said articles from said conveying means into said tank in a direction transversely of the length of said articles, and means for removing said articles longitudinally from said tank when they reach said non-advancing grooves in said screws.

3. In apparatus for coating elongated objects, a tank for holding a bath of coating material in liquid form, a plurality of conveying screws having spaced apart axes, said conveying screws having pick-up ends disposed to engage an elongated object at spaced points along its length and having threads thereon portions of which progressively increase in diameter in the direction of feed of said object and extend into said bath, and a plurality of object supporting skids adjacent said conveying screws and extending into said tank in spaced apart relation along the length of said objects being coated.

4. In apparatus for coating elongated objects, a tank for holding a bath of coating material in liquid form, a plurality of conveying screws having spaced apart axes, said conveying screws having pick-up ends disposed to engage an elongated object at spaced points along its length and feed same into said tank in a direction transversely of the length of said object, said conveying screws having threads thereon portions of the diameters of which increase in the direction of feed of said object and extend into said bath, and a plurality of object supporting skids adjacent said conveying screws and extending into said tank in spaced apart relation along the length of said objects being coated, said skids having object engaging edges contoured to correspond to said diameters of said conveying screws and spaced below said screws whereby said object is held in feeding engagement with the threads of said screws.

5. In apparatus for coating elongated objects, a tank for holding a bath of coating material in liquid form, conveyor means for continuously moving a series of elongated objects in a direction transversely of their length up to said tank above the surface of said coating material therein, a plurality of conveying screws having their axes spaced apart lengthwise of the objects being coated and extending in the direction of movement of said objects on said conveyor means and disposed above the coating material level in said tank, said screws having threads thereon portions of which increase in diameter in the direction of advance of the threads and extend into said bath, a plurality of object supporting skids extending into said tank adjacent said screws and spaced apart along the length of said objects being coated, the diameters of said portions of said threads on said conveying screws increasing differently relative to each other along the screw axes whereby elongated objects leaving said conveyor means, will be moved in succession transversely of their length into said bath of coating liquid and one end of each of said objects will be moved through a different vertical travel than the other end, and means for maintaining a constant angular relationship between said screws.

6. In apparatus for coating elongated objects, a tank for holding a bath of coating material in liquid form, conveyor means for continuously moving a series of elongated objects in a direction transversely of their length up to said tank above the surface of said coating material therein, a plurality of conveying screws having their axes spaced apart lengthwise of the objects being coated and extending in the direction of movement of said objects on said conveyor means and disposed above the coating material level in said tank, said screws having threads thereon portions of which increase in diameter in the direction of advance of said threads, and a plurality of object supporting skids extending into said tank below said screws and spaced apart along the length of said objects being coated, the diameters of said portions of said threads on said conveying screws increasing differently relative to each other along the screw axes whereby elongated objects leaving said conveyor will be moved in succession transversely of their length into said bath of coating liquid and one end of each of said objects will be moved through a different vertical travel than the other end, said conveying screws having non-advancing grooves at their delivery ends and having magnet means I effective over a portion only of the periphery of said grooves, said magnet means being circumferentially located on said conveying screws whereby, during part of a revolution only, an article being handled will be moved lengthwise thereby in exiting direction, means for simultaneously rotating said conveying screws, and means for maintaining a constant angular relationship between said conveying screws.

7. In apparatus for coating elongated objects, a tank for holding a bath of coating material in liquid form, means for continuously moving a series of elongated objects in a direction transversely of their length up to said tank above the surface of said coating material therein, a plurality of conveying screws having their axes spaced apart lengthwise of the objects being coated and extending in the direction of movement of said objects on said article moving means and disposed above the coating material level in said tank, said screws including portions having threads thereon that increase in diameter in the direction of advance of said threads, a plurality of object supporting skids extending into said tank below said screws and spaced apart along the length of said objects being coated, the diameters of said portions of said screws increasing differently in different screws whereby elongated objects leaving said article moving means will be moved in succession transversely of their length into said bath of coating liquid and one end of each of said objects will be moved through a different vertical travel than the other end.

8. In apparatus for coating elongated objects, a tank for holding a bath of coating material in liquid form, means for continuously moving a series of elongated objects in a direction transversely of their length up to said tank above the surface of said coating material therein, a plurality of conveying screws having their axes spaced apart lengthwise of the objects being coated and extending in the direction of movement of said objects on said article moving means and disposed above said coating material level in said tank, said screws including portions having threads thereon that increase in diameter in the direction of advance of said threads, a plurality of object supporting skids extending into said tank below said screws and spaced apart along the length of said objects being coated, the diameters of said portions of said screws increasing differently in different screws whereby elongated objects leaving said conveyor means will be moved in succession transversely of their length into said bath of coating liquid and one end of each of said objects will be moved through a different vertical travel than the other end, magnet means on one of said conveying screws effective over a portion only of the periphery at the exit end of the screw, said magnet means being circumferentially disposed on said screw to move an article being handled lengthwise in exiting direction during a portion of a revolution of said screw, means for simultaneously rotating said conveying screws, and means for maintaining a constant angular relationship between said conveying screws.

9. Apparatus for continuously coating elongated articles including, conveyor means for moving a series of said articles in parallel relation in a direction transversely of their length, a housing for said conveyor means adapted to maintain a gaseous atmosphere therein, means for heating said articles as they are moved through said housing by said conveyor means, a coating tank within said housing at the discharge end of said conveyor means, a plurality of rotatable conveying and sinking screws disposed in said housing and having their axes extending across said coating tank in a direction transversely of the length of said articles, said screws having article pickup thread portions at the discharge end of said conveyor means adapted to pick up articles in spaced series relation from said conveyor means, said screws having progressively enlarging thread portions of increasing diameter merging with said pick-up thread portions and extending into said coating tank, means in said tank for supporting and guiding articles moved by said screws whereby said articles are held in engagement with said enlarging thread sections and moved into said tank in a direction transversely of their length, magnetic means on said screws for moving said articles endwise out of said tank when they reach the discharge ends of said screws, means for interconnecting said screws to maintain a fixed angular relation therebetween, and means for rotating said screws in a direction to traverse said articles from the discharge end of said conveyor means into said tank in a direction transverse of their length and then out of said tank in endwise direction.

10. Apparatus for continuously coating elongated articles including conveyor means for moving a series of said articles in parallel relation in a direction transversely of their length, a housing for said conveyor means adapted to maintain a gaseous atmosphere therein, means for heating said articles as they are moved through said housing by said conveyor means, a coating tank within said housing at the discharge end of said conveyor means, a plurality of rotatable conveying and sinking screws disposed in said housing and having their axes extending across said coating tank in a direction transversely of the length of said articles, said screws having article pickup thread portions at the discharge end of said conveyor means adapted to pick up articles in spaced series relation from said conveyor means, said screws having enlarging thread portions of increasing root diameter merging with said pick-up thread portions and extending into said coating tank, spaced apart skid means in said tank for supporting and guiding articles moved by said screws whereby said articles are held in engagement with said enlarging thread sections and moved into said tank in a direction transversely of their length, magnetic means on said screws for moving said articles-endwise out of said tank when they reach the discharge ends of said screws, means for interconnecting said screws to maintain a fixed angular relation therebetween, and means for rotating said screws in a direction to traverse said articles from the discharge end of said conveyor means into said tank in a direction transverse of their length and then out of said tank in endwise direction, the threads of said enlarging thread sections of two of said feed screws increasing in diameter differently from each other and said spaced apart skid means varying in contour whereby each article will be inclined lengthwise from a horizontal into a tilted position during its travel through said tank.

11. In pipe galvanizing apparatus having a galvanizing tank adapted to hold a bath of molten zinc, a conveying and sinking screw having a pick-up end and a discharge end and rotatably supported above said bath with its axis extending thereover, said screw having a continuous thread extending from one end to the other, said thread at said pick-up end being of constant diameter and progressively increasing in diameter above said bath whereby said thread enters said bath and is adapted to sink a pipe being conveyed by said screw into said bath, and a discharge groove at the discharge end of said thread to which said thread connect and into which pipes are delivered by said thread, and means carried by said screw and effective on a pipe when in said discharge groove to move said pipe longitudinally in a direction normal to the direction of movement imparted to said pipe by said thread.

12. In apparatus for coating elongated objects, a tank adapted to hold a bath of coating liquid, a conveying and sinking screw having a pick-up end and a discharge end, said screw having a double thread extending from one end to the other, said thread including a portion of progressively increasing diameter disposed above said tank whereby said thread enters said bath and is adapted to convey a pipe to said bath and sink the pipe therein, and means for rotatably supporting said screw above said bath with its axis extending thereover.

References Cited in the file of this patent UNITED STATES PATENTS 545,430 Lewis Aug. 27, 1895 561,712 Lynch June 9, 1896 682,147 Lynch Sept. 3, 1901 947,440 Greenfield Jan. 25, 1910 1,851,734 Smith Mar. 29, 1932 1,869,324 Free July 26, 1932 1,935,087 Free Nov. 14, 1933 2,326,844 Ely Aug. 17, 1943 2,804,841 Salkeld Sept. 3, 1957 2,906,238 Heaton et al. Sept. 29, 1959 2,951,491 Olson Sept. 6, 1960 

